Ballast resistor.

[Darrell Kinnan]

Installed a new ballast resistor on a rough running 37 engine. Started the engine and the resistor started smoking. Put the original back on, it's made out of ceramics, it didn't smoke but reach to 300 degrees. Should the resistor run this hot, if not, what could be the problem? Obviously the new ballast resistors can't stand the heat as they are not ceramic.

Always grateful for your help,
Darrell

[RalphM]

They do get warm, not sure of the actual temp.
If this is ignition resistor, they still make ceramic ones. Do a search for part number. It has been discussed here before.

[flatheadmurre]

If the coil is drawing to much current....being partial shortened or some other issue the resistor will heat up more then it should.
They should heat up a fair bit...that´s part of the design.
Those chinese bambo versions from the company whos name we shall not mention are just plain junk...you´re better of fixing your old one...

[George/Maine]

The resister is about .5 ohms but you must have a watt rating of 10
See if you can get one on line .5ohms 10 watts

[BillM]

See if you can get one on line   .5ohms 10 watts

Ignition ballast resistors have a positive temperature coefficient; as they get hotter their resistance increases. Normal power resistors have a neutral temperature coefficient so don't react like ballast resistors. There was a post recently that listed different values of ballast resistors from NAPA I believe. That would be what one would want if you need a special resistance.

[JSeery]

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All of these are higher value than what you need for a stock Ford application.

•#ICR23 – 1.20 ohms
•#ICR11 – 1.35 ohms
•#ICR34 – 1.40 ohms
•#ICR37 – 1.60 ohms
•#ICR35 – 1.80 ohms
•#ICR13 – 1.82 ohms
Lucas* 3BR (1.3 - 1.4 Ohms)
Mopar* DCC-4529795 (1.40 Ohms)
Accel* ACC-150250 (1.35 Ohms)
Standard* RU-4 (1.35 Ohms)
Standard RU-23 (1.20 ohms)
Standard RU-37 (1.40 Ohms)

[rotorwrench]

We need to know if this is a stock 6-volt system. Resistors use some power to drop voltage and control current since they are a load device. They will get hot so they use ceramics & place them on a board that can take some heat. Ford generally placed the board in an area where they will be somewhat protected from hazards.

[George/Maine]

I think the 6 volt coils need about 3 amps or 4.5 volts to work. With no special meters ,only a volt meter if you measure 1.5 volts across the resister that should be good. By putting a larger 1.5 ohms you cut the amps to 2 amps and the coil voltage to 3 volts. So with a .5 ohm 10 watt this should work if you can't find a original resister.

[Init1]

Be careful you use the right resistor. If you use one with too much resistance it will reduce the juice to the plugs and soot them up so much they will misfire.
If you see black sooty plugs your resistor is too big.

[G.M.]

Originally Posted by Init1

Be careful you use the right resistor. If you use one with too much resistance it will reduce the juice to the plugs and soot them up so much they will misfire.
If you see black sooty plugs your resistor is too big.

This sounds like more of a guess than fact. Truth is the engine will
run good on 4 volts to the coil and also good in the 3.5+ range but
when you get below 3.5 it may not even start. In the lower range
sometimes it will start just as you release the starter the engine is
still spinning and the voltage to the coil increases from the voltage
increase when the starter disengages. Much over 4 volts will cause
the points to arc and pit them. G.M.

[Darrell Kinnan]

Here's what I'm getting with the engine not running:

6 volts on the battery
2 volts at the coil
6 volts on the ignition side of the resistor
2.5 volts on the coil side of the resistor

Is the resistor taking too much from the coil? Engine starts but runs real rough.

Darrell

[Init1]

Just like I said......

[George/Maine]

Originally Posted by Darrell Kinnan

Here's what I'm getting with the engine not running:

6 volts on the battery
2 volts at the coil
6 volts on the ignition side of the resistor
2.5 volts on the coil side of the resistor

Is the resistor taking too much from the coil? Engine starts but runs real rough.

Darrell

I like to test when running, measure across resister.
I would buy a resister from
Resistor Fuse Terminal Block
1933 - 37
40-12250
dennis-carpenter
about $30 looks like original.

[JSeery]

Originally Posted by Darrell Kinnan

Here's what I'm getting with the engine not running:

6 volts on the battery
2 volts at the coil
6 volts on the ignition side of the resistor
2.5 volts on the coil side of the resistor

Is the resistor taking too much from the coil? Engine starts but runs real rough.

Darrell

Several issues here, but the big one appears to be the voltage drop across the ballast resistor. The coil needs a min of 3.5v (as already stated) and is better at around 4.0v. The battery should be greater than 6v not running, more in the 6.2-6.3 range and somewhere above 7v running.

[BillM]

If the coil is drawing to much current....being partial shortened or some other issue the resistor will heat up more then it should.

Agree with flatheadmurre.

[JSeery]

Originally Posted by BillM

Agree with flatheadmurre.

Don't think so with these voltage numbers.

[flatheadmurre]

If the coil is shorted out having a lower resistance then it should have you get readings like this.
Or if the ballast resistor has a bad connection between the resistance wire and the connection points giving it a higher value then it should have.
Is the coil heating up more then normal ?

[Darrell Kinnan]

Thanks for all replies. I've learn that ballast resistors can get red hot. I put the old one back on and it seems to be working ok with at least 2.5 volts to the coil. Waiting for Skip to rebuild the coil and have received a distributor rebuild back from Cliff Green. Hope to be on the road soon. DK

[Paul Bennett]

My 1950 car havingh no resistor I'm want to ask, what year did resistors no longer become standard on Ford engines?

[TJ]

I think your '50 went to the coil with the internal resistor.

[rotorwrench]

The 8BA starting with pickups in 1948 had the first can type coils that were designed to work with no ballast. The ballast came back in a new form for 1956 with the change over to 12-volt systems.

Many of the reproduction ballast resistors for the early cars have been problematic. A good original would be preferred over the reproduction. Some of the reproduction ones have the white insulator but I don't know if those are ceramic or not. They were made to look original but not necessarily work as well. Some folks solder the ends to keep good contact. A lot of repro stuff is still pretty pitiful in its manufacture. Especially with the ignition components.

[rotorwrench]

Delete repete

[JSeery]

Originally Posted by Darrell Kinnan

I put the old one back on and it seems to be working ok with at least 2.5 volts to the coil. DK

2.5V is no where near enough at the coil. It needs to be 3.5 to 4.0V.

[BillM]

A normal system will have 4V at (across) the coil and a .5 ohm balllast resistor which will then have 2.5 V across the resistor. This results in about 4 amps in the (series) circuit. If we assume the ballast resistor is about .5 ohms in this thread then it has about 4 volts across it which computes to about 8 amps flowing. When he gets his coil back from Skip I think his resistor will stop glowing red and he will then have more like 4 volts across the coil.

[56markII]

My 1950 Mercury still uses a resistor on the ignition coil WITH a resistor bypass relay that bypasses the resistor while cranking to compensate for the drop in voltage while cranking. The mounting tab I accidentally broke the spot welds so I soldered the tab back on. Now I'm looking for a replacement but cannot find it in the OEM parts manual. I cannot see ANY reason why one would want an internal resistor within the coil?? Ford for years along with other makes had a bypass method for when the starter wad used to compensate for the lower voltage. In the newer Fords they had two terminals instead of one like my Mercury. One was from the Starter switch and the other was a bypass going directly to the coil bypassing the resistor. My metal housing style solenoid on my Mercury only has one terminal and that goes to the starter button on the dash. This ignition relay has three terminals, one wired to the solenoid to activate the relay while cranking, and the other two terminals has the typical 1940's resistor screwed to these two terminals. One has a wire coming out of the engine harness and the other has a wire going to the coil. When the relay is activated it bypasses and directs the power directly from ignition switch to the coil. I will repair the damage but I continue to try to find a part number so hopefully I can find a spare/replacement!

[petehoovie]

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As designed by 'supereal' - here and at the EFV8 Club site >


Using a diode to bypass the ignition resistor:

[JSeery]

I have never seen that setup before, seems like a cool idea!

[56markII]

In my opinion as well it is a cool setup to improvise a bypass for higher voltage BUT if I cannot find a replacement if it fails I to was pondering on stuffing a silicon rectifier in the case of the relay from the starter solenoid circuit other than attempting to hide a smaller modern relay in there. We don't have a "RatShack" up here anymore as far is I know?? RadioShack has been under Tandy name for years but I think is gone now up here in the Snow Mexican Republic of Canuckastan 😂LOL. This is a Canadian Mercury but it is not a Monarch. Otherwise it looks the same with the exception of the air filter being straight back behind the Holley 885 instead of off to the side like I see in some American Mercury pictures. On the other hand my American OEM parts manual also shows the filter location like mine as well. Other than that my heads have C8CM on them and below that "Made In Canada" and at the end of the day work the same. I have a number of cores laying around with coils etc. and they all look the same, most likely all needing external resistors. Hopefully the picture is clear enough and the resistor looks like some OEM 1940's Ford resistors I have seen for sale. Ron was puzzled about it as well so I sent pictures and perhaps?? the American built have the same thing? but perhaps located elsewhere? If you look closely you will notice the wiring has the protective vinyl tube just like the ignition wire coming out of the engine wiring harness so I suspect it is factory. Mine is located directly behind the battery box bolted to the inner fender with the typical Lag screws like the horn relay. The only other differences I can discover is my original radio is a Canadian Macaroni, my terminology for Marconi and it only has one audio output tube instead of a pair like the Zenith used south of the boarder. Other variations I have indicated to Ron is the fact that pretty much everything in the car picture of things had their engines painted Beige instead of the variety of colors the American cousins had. Being a mechanic for 38 years allowed me to figure out an exact match for powertrain paint and that is early Cummins Beige. 1949-54 Ford/Mercury had the flatheads, bell housings, and transmissions painted this color with the exception of starter, generator, fan, oil pan, filler, draft pipe etc. and sorry I don't know what color the truck engines are. Earlier than 1949 is a different story on this topic. Trucks are most certainly not as common as cars but then again not much that is old is around anymore. There is also a small circuit breaker mounted on this assembly as well indicating a well built product which is another reason why it still survives today.

[56markII]

Very little difference as far as I can tell and even my assortment of accessories match what are in the OEM accessories brochure such as the little white bubble light in the trunk, the quaint looking rear speaker, etc.

[flatheadmurre]

If you have a starterbutton that grounds to activate the solenoid a horn relay does what is needed for that setup.
Resistor mounted between power in and out on horn relay.

[big job]

Much has been said about these resistors 'here' I'm still stumped, why a resistor only
on ford products. Has to be something with an original coil? Beer can coils don't need
resistors, per Motors book, my 1936 Plymouth has no resistor as well as 1950 F8 no resistor: Although my 46 car now has a can coil, maybe I should bypass the resistor, or
leave it be? I just want to know why the need for a resistor with 6 volts only on Ford products, and I never heard of a resisted 6vt coil either. sam

[flatheadmurre]

The ballast resistor is a cost effective hot start device...no moving part/contacts...not expensive...ford used the cheapest bulletproof way around !
The resistor takes down the current to get more life out of the points...but still gives you a hot spark at startup.

[56markII]

Ford has used ignition resistors for years even in the 70's and why would you have one in the coil when it can be bypassed by the starter solenoid? My 56 Continental has that typical two smaller terminal solenoid used for years and beside the coil inches away from the solenoid is also the ignition resistor, the type with the metal perforated shield. To those that say it isn't needed just bypass it and watch your points die a horrible death! If my Canadian model (not a Monarch) uses this obvious OEM device it is probably provided so these cars had a better chance of starting at -40 to -45 in our Siberian climate! Put a volt meter on your battery and crank the engine for 10 continuos seconds and see what the voltage drops down to and keep in mind the voltage will be lower at -40 combined with engine oil being like grease at that temperature.

[rotorwrench]

On the Ford Mallory type vacuum brake distributors, there were several different coils manufactured by Ford and Mallory over the years of the pre-8BA V8 engines. These coils have a much different coil core and winding set up than the cylinder or can type coils. The design required the current control to give reliability for a long period of use. A hot coil is not a good thing plus many were right next to the engine. Their saving grace was the air flow at road speed but at an idle they get hot. The ballast kept some of the heat on the outside and in another location. Can type coils never did use ballasts on 6-volt. The model A used no ballast either. A person can get a spark from them if they use a low Ohm ballast but it just isn't really a problem with them.

Newark likely carries an Ohmite high watt .5 Ohm resistor that would work as a ballast for the vacuum brake type distributor coils. Here is one that is close but there are likely others.
https://www.ohmite.com/catalog/270-s...attribute-ohms

Here is another one (top one) of a different type.
https://www.ohmite.com/catalog/20-se...attribute-ohms

[petehoovie]

I don't think that the ballast resistor was unique to just Ford cars. My '57 Chevy had one....

[JSeery]

As did a lot of Chryslers, the box shaped carminic ones are often referred to as Chrysler ballast resistors.

[BUBBAS IGNITION]

GUYS WE ARE BEATING THIS HORSE TO DEATH.......

All ignition systems are designed to have a usefull life. On a point system it was designed to allow enough current to flow thru the coil (current is constant in a series circuit) Only voltage drops off after the resistor. Voltage arc is what kills the points... OEMs design the system as well as the ignition coil to control this in all aspects of operation.
1-battery
2-ignition on off
3-wire to the coil ( or to the resistor and then to coil)
4-coil and coil windings
5-final resitance to distributor from coil
6-then the distributor with condensor ( arc control) and points
7-to a good ground to complete the circuit..

Typically the circuit will have a ballast (external) resistance or the coil windings may serve as w resistance ( voltage drop)
Coils dont have actual resistors in them..
Early Fords used a .5 resistor and a .6 ignition coil primary winding. So total resistance is 1.1 ohms divided by 6 volts for a amp flow of 5.45 amps for a good strong spark.
THEN things start going wrong????

Some remove this .5 resistor , amps now is 12 amps thru the entire circuit causing heat build up and damage to points , coil etc. ( may run really good for a while but will catch up with you for sure)

THEN we start the engine and gen volts increase to 7.2-7.5 volts resistance needs to increase and it does due to higher volts and actual heat of the resistor .
Also the final wire to distributor is a fine stranded wire to help burn off this final little blast of voltage .

I have seen this lead replaced with 10 gauge , bad/bad !!!

NOTE....most resistors will smoke when new ..........our hope is that they quit someday.....

[4dFord/SC]

Originally Posted by BUBBAS IGNITION

I have seen this lead replaced with 10 gauge , bad/bad !!!

What is the recommended guage?

[BUBBAS IGNITION]

Originally Posted by 4dFord/SC

What is the recommended guage?

Varies per factory etc , but always a finely stranded cable for that little hit of voltage drop protecting the points. Usually a volt drop of .05-.01 volts... In a perfect world on a running engine it would be a final drop of .01volts or damn near zero....
Actually we have bench tuned a couple to be very very low close to the zero mark.....
I see cars and hot rods at shows where the customer has neatly wired the car with huge wire all the way into the points ........NOT GOOD but pretty i guess..

[56markII]

Beating it to death perhaps but isn't it amazing how many of us are totally unaware of what is and what isn't?? My argument is why wouldn't you have an ignition resistor bypass? It is well known why they had them and this is indicated by the solenoid many Fords, Mercury, and Lincoln have such as anything post 1955 with the somenoid with two terminals on top not one. One is power to energize the solenoid and the other is the resistor bypass for higher voltage supply when the starter draws. Being a Canadian (non Monarch) Mercury this is probably provided for our very nasty climate for hotter spark in our Siberian climate. If there is a 6 volt solenoid period correct with the extra bypass terminal my relay complete with a circuit breaker and resistor attached would be eliminated and the resistor would be elsewhere. Supply and demand and what they had on hand dictates what they used and my Continental Mark II is a very good example of this! There are many grey areas of when things were used and not used creating many arguments and speculation as well including a heated debate in the past which one was the first 1957 model. I looked through my OEM 1949-51 and 1949-53 parts manuals including my 1949-51 Lincoln manuals all Ford and not other publications and nothing appears BUT these are all American not Canadian and while we are at it the date of the flathead is 1932-53 but up here and probably Australia is 1954. I will leave this device on my inner fender because it still works and serves a usefull purpose.

[BUBBAS IGNITION]

Originally Posted by 56markII

Beating it to death perhaps but isn't it amazing how many of us are totally unaware of what is and what isn't?? My argument is why wouldn't you have an ignition resistor bypass? It is well known why they had them and this is indicated by the solenoid many Fords, Mercury, and Lincoln have such as anything post 1955 with the somenoid with two terminals on top not one. One is power to energize the solenoid and the other is the resistor bypass for higher voltage supply when the starter draws. Being a Canadian (non Monarch) Mercury this is probably provided for our very nasty climate for hotter spark in our Siberian climate. If there is a 6 volt solenoid period correct with the extra bypass terminal my relay complete with a circuit breaker and resistor attached would be eliminated and the resistor would be elsewhere. Supply and demand and what they had on hand dictates what they used and my Continental Mark II is a very good example of this! There are many grey areas of when things were used and not used creating many arguments and speculation as well including a heated debate in the past which one was the first 1957 model. I looked through my OEM 1949-51 and 1949-53 parts manuals including my 1949-51 Lincoln manuals all Ford and not other publications and nothing appears BUT these are all American not Canadian and while we are at it the date of the flathead is 1932-53 but up here and probably Australia is 1954. I will leave this device on my inner fender because it still works and serves a usefull purpose.

I dont disagree with any of this, cars and circuits have changed a lot per manufacture.....

[Tinker]

"ol'henry" had a few threads on a diode, not his idea (posted great pictures). It's pretty easy set up. A diode restricts flow of electrons in one direction.


Or just buy a 6v ford tractor 4 post solenoid. Not correct looking, but the full coil bypass post is built in.
https://www.steinertractor.com/ABC39...SABEgLLifD_BwE


Never needed either, so far.


.